Internal joint bracing system and suture anchoring assembly therefore

ABSTRACT

An internal bracing system is disclosed for stabilizing a joint such as the knee, shoulder, ankle or the like. The internal bracing system includes an extra-articular tension band mechanism and an anchor assembly therefore. The internal bracing system adds substantial control to unstable joints which is effective in limiting the pathological joint motions and internal slippage. The anchor anchoring assembly designed to affix a tethering device to various bony structures which form a joint, for the purpose of providing stability. The anchor assembly includes an anchor and a set screw. A double helix thread/chamber structure between the anchor and set screw securely holds the tether without binding.

This application claims benefit of priority under 35. U.S.C. §119(e) ofPCT application PCT/US10/31532 filed on Apr. 18, 2010, which claimspriority to U.S. provisional patent application 61/170,446 filed on Apr.17, 2009, the contents of which are expressly incorporated herein byreference. U.S. patent application Ser. No. 12/763,179 is incorporatedby reference. The contents of all references cited herein are expresslyincorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention is generally directed toward an internal bracing systemfor the knee, shoulder, ankle or the like. The internal bracing systemis designed to be located on the medial, lateral, anterior, or posterioraspect of the joint in a manner effective to control excessive laxity ortraumatic rotatory and/or translational instability of the joint. Theinvention is more particularly directed toward an internal bracingsystem having an extra-articular tension band mechanism and anchoringassembly. The anchoring assembly is designed to affix a tethering deviceto various bony structures which form a joint.

2. Discussion of Related Art

It has been observed that subsequent to specific joint instabilitiesafter ligament injury, trauma or chronic laxity (which can be morecommon in certain populations with high demands and geneticpre-disposition); there is a need for specialized internal bracing orligament augmenters. Specifically, as seen in these populations, therecan be severe combined ligament insufficiency and/or deficienciesleading to instability of the joint causing early progressive jointwear, arthritis, pain and dysfunction.

Existing externally worn joint braces have been used for years but havebeen uncomfortable and ineffective in providing the type of control andstability needed to control pathologic sequele of an unstable joint. Theother traditional option of intra-articular ligament replacements arecomplex to install, have high failure rates and are generally noteffective over time. Thus, there has been a general failure of externalbrace capacity and surgical intracapsular (complex positioning required)ligament reconstructions to control the high joint functional demands,e.g. control of the unstable motion and/or joint slippage or control thebuckling or subluxation at high speed/stress motions causing the jointto still give away.

As a result of these observations, the present inventors have sought torestabilize the effected joints, by providing to these stretched or tornligaments, augmenting or reinforcing structures, for example to extracapsular knee structures, thereby providing an ‘internal bracing’ likestructure which can be surgically created by a simple, low-costtechnique. This robust extra-capsular augment or internal bracing of thejoint controls stability using simple artificial reinforcers or tensionbands. This is done through this invention's ability to control thearticular position of the particular joint allowing this to return to amore normal motion, while simultaneously limiting the abnormaltranslations and rotations, and thereby lessening abnormal stresses.

SUMMARY OF THE INVENTION

The present invention adds substantial control to unstable human jointsthrough an ‘internal bracing’ extra-capsular approach which is effectivein limiting the pathologic joint motions and internal slippage whichleads to the pathologic, destructive unstable motions and high stressesseen commonly post-trauma and in cultures with genetic laxity and/orhigh demand knee performance, e.g. such as high stretch states where theligaments are permanently loosened, lengthened or torn. By adding this‘internal brace’ control it is expected to prevent or slow progressionof arthritic wear, pain and instability of the joints in theseindividuals.

These artificial ligament anchors allow for fixation across a joint frombone to bone, while permitting the tether to move through a range ofpositions without damaging the tether at the anchor interface.

The ‘internal brace’ can be positioned as required to augmentdysfunctional ligaments of the unstable joint as needed for goodfunction. Multiple anchors can be used and the position of the anchorscan be confirmed with a trialing template and fluoroscopic control,which will make the technique even simpler.

This robust extra-capsular augment or ‘internal brace’ of the jointcontrols stability using simple artificial reinforcers or tension bands.This is done through the invention's ability to control the articularposition of the particular joint allowing this to return to a morenormal motion at the same time limit the abnormal translations androtations which lessen abnormal stresses.

Accordingly, it is a primary objective of the instant invention toprovide an ‘internal bracing’ concept which allows for high functionactivities while controlling the damaging, pathological instability orslippage seen in patients with all type of joint dysfunction. It is afurther objective of the invention to provide a system for more easilysurgically tacking these ligament augments in place therefore allowing awide range of generalized, less specialized surgeons to effectively usethis technology.

It is yet an additional objective to provide a novel screw anchor with acentral set screw made from biocompatible, high strength materials andincorporating a synthetic or biologic tether to be securely anchored tobone.

It is a still further objective to provide a method for attaching thetether to the anchor which dynamic movement of the tether without highrisk of failure of the tether, thereby providing a unique constructwhich can utilize large radii bending, universal joints, and/ortensioners.

Other objects and advantages of this invention will become apparent fromthe following description taken in conjunction with any accompanyingdrawings wherein are set forth, by way of illustration and example,certain embodiments of this invention. Any drawings contained hereinconstitute a part of this specification and include exemplaryembodiments of the present invention and illustrate various objects andfeatures thereof.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a partial section view, taken along lines 1-1 of FIG. 2,illustrating a suture anchoring assembly according to an embodiment ofthe present invention;

FIG. 2 is a top view illustrating an internal bracing system accordingto an embodiment of the present invention connected to a knee joint;

FIG. 3 is a side view illustrating the internal bracing system of FIG.2;

FIG. 4 is a side view of an anchor member according to an embodiment ofthe present invention;

FIG. 5 is a bottom view of the anchor member illustrated in FIG. 4;

FIG. 6 is a top view of the anchor member illustrated in FIG. 4;

FIG. 7 is a perspective view of the anchoring member illustrated in FIG.4;

FIG. 8 is a perspective view of the anchoring member illustrated in FIG.4;

FIG. 9 is a section view taken along lines 9-9 of FIG. 4;

FIG. 10 is a side view of a set screw according to an embodiment of thepresent invention.

FIG. 11 is a top view illustrating an internal bracing system accordingto an embodiment of the present invention on a knee joint.

DETAILED DESCRIPTION

The invention will now be more specifically described with reference tothe aforementioned FIGS. 1-10.

In accordance with an embodiment of the present invention a novel anchorassembly 1 is securely anchored to bone to attach a synthetic orbiologic tether or suture 20. (Tether and suture are used interchangablyherein to refer to the material attached to the bone anchor assembly forforming an internal bracing system according to an embodiment of thepresent invention.) The anchor assembly 1 includes an anchor member 5and a central set screw 10. The anchor member 5 and set screw 10 aremade from biocompatible, high strength materials. Details of the anchormember 5 are illustrated in FIGS. 4-9. Details of the central set screw10 are illustrated in FIG. 10. The tether 20 is connected to the anchorassembly 1 through interaction of the anchor member 5 and the set screw10. The attachment of the tether 20 allows dynamic movement of thetether 20 without high risk of failure of the tether. This uniqueconstruct can utilize large radii bending, universal joints, and/ortensioners. The locking of the tether 20 to the anchor assembly 1 isachieved by a novel design of the head of anchor member 5, interior plug14 therein, and the set screw 10. The locking is performed in such amanner that the strength of the tether is not compromised.

The surface geometry and/or coating of the anchor member 5 permits atorsionally stable fixation to bone and allows good bony on-growth. Theanchor 5 is designed to be pushed, e.g. hammered, into place in thebone. It has a cylindrical body 6 and a wider cylindrical head 7.Finistrated surface structures 30 extend longitudinally along the outersurface of the cylindrical body 6 at various locations around theperiphery. The finistrated surface structures 30 provide torsionalstability to the anchor member 5. Alternatively, the outer surface ofthe cylindrical body 6 could include threads (not shown) so that theanchor member 5 could be screwed into the bone. However, the pushed inanchor member is deemed preferable since screwing in of the anchor wouldlikely require right and left hand screw threads depending on directionof force on the tether. The risk of using the wrong screw—resulting infailure to maintain tension of the tether—is thus eliminated by thepreferred construction.

The head 7 has a cylindrical channel 21 narrower than the top 12 a andbottom 12 b thereof. A slot 4 is formed across the head. The slotextends to the level of the bottom 12 b of the head. The channel 21 andslot 4 operate to retain and guide the tether into the center of theanchor member 5.

A bore 8 extends along the central axis of the head 7 and body 6 of theanchor member 5. A double helix thread/channel structure 9 extends alongthe interior of the bore 8. The double helix thread/channel structureends before the bottom of the bore. A plug 14 is positioned in thebottom of the bore 8 at the end of the double helix thread/channelstructure 9.

Preferably, the anchor member 5 is formed of Commercial Pure TitaniumCP4 Ti, a titanium alloy, or a suitable polymeric material. The body 6could also be hydroxyapatite coated (HA coating) to enhance boneongrowth. If high strength is a requirement for the anchor, Ti alloymaterial should be used. The surface of body 6 of anchor member 5 ispreferably rough blasted with Ra of approximately 5 for good boneongrowth. The head 7 of anchor is preferably polished so no rough edgesinterface against the tether material. The plug 14 at bottom of bore 8should be a biocompatible elastomeric material, e.g. a polyurethane,which material is generally available in different grades of hardness.The material for the plug 14 and hardness should be selected to impederotation of the set screw 10, as discussed below.

The set screw 10 has a cylindrical construction with a double helixthread/channel structure 40 around the periphery thereof. The doublehelix thread/channel structure 40 mates with the similar structure inthe interior of the bore 8 of the anchor member 5. The relationshipbetween the double helix thread/channel structure 40 of the set screw 10and the double helix thread/channel structure 9 of the anchor member 5leaves space between the set screw and bore of the anchor member 5 toreceive and retain the tether. One end of the set screw 10 includes arecess 12 to receive the tether. The other end of the set screw 10 has ahexagonal bore 13. The hexagonal bore 13 can receive a tool for rotatingthe set screw 10 to insert it into the anchor member 5. Of course,another mechanism, such as a Torx bore or slot for a screwdriver, couldbe used to rotate the set screw 10 for insertion.

Preferably the set screw is made from Ti Alloy Ti6A14V(Ti-Aluminum-Vanadium) or Ti6A17Nb (TAN Ti-Aluminum-Niobium) or asuitable polymeric material, e.g. PEEK. Preferably, the set screw has asmooth surface finish.

To attach the tether to the anchor assembly 1, the tether 20 is locatedin the recess 12 of the set screw 10. As the set screw 10 is threadedinto the bore 8 of the anchor member 5, the tether 20 is guided into thedouble helix channel such that one leg of the tether is guided into onehelix while the second leg is guided into the second helix of the setscrew 10. Referring to FIG. 1, letter designations “A” and “B” referencethe first and second legs of the tether 20 as it follows the doublehelix construction 40. As the set screw 10 is tightened to the bottom ofthe bore 8, the plug 14 compresses the tether 20 against the end of theset screw 10 and maintains force against the set screw 10 so that theset screw 10 is locked and prevented from rotating. The path of thetether 20 around the head 7 of the anchor member 5 and into the setscrew 10, along with the wrapping through the channel in the set screwprovide a gradual transfer of force from the tether to the anchor. Bythe time the tether 20 at the recess 12 of the set screw 10 iscompressed by the plug 14 at the bottom of the anchor, the loadremaining in the tether 20 is minimized. This allows for locking of thetether without knots. Knots cause sutures (tethers) to bend aroundcorners of very small radii which cause high strains and early failureof sutures.

Additional features to prevent loss of strength of the tether at theanchor are the make-up of the tether and the radii and the shape of thepath for the tether to be locked into. The tether material has highaxial strength and high axial stiffness and may be either synthetic,biologic or hybrid. The radii of the path of the tether in thescrew/plug and the set screw are made as large as possible to minimizestrain in the individual filaments of the tether. By correct positioningof two, three or more ‘internal ligaments’ and adjusting of the tether,the internal brace construct can provide augmentation to almost anyjoint ligament. A simple jig (not shown) can be used for trial positionsof the anchors to confirm the improved stability/function of the jointprior to final insertion of the anchors. This makes the surgery easy fora basic surgeon to perform. The function and position of the joint canbe guided by navigation techniques of ultrasound or fluoroscopicimaging.

Various materials and configurations may be used as a tether in internalbracing system according to the present invention. Preferred fiber foruse with the anchor assembly of the invention is that of oriented, highmodulus, ultra high molecular weight polyethylene, such as DYNEEMA® fromDSM, Netherlands, or SPECTRA® from Honeywell, USA. Preferred diameter ofthe fiber is between 10 and 20 micrometers, more preferably about 15micrometers. Although any configuration of fibers is contemplated by theinvention, in a preferred embodiment, fibers are left free from eachother, as in yarn; e.g. neither diffusion bonding nor braiding is usedin production. The anchor assembly of the present invention securelyattaches to and holds all of the individual fibers in bundle. The use offree fibers prevents rubbing and stresses which can occur with braidedor bonded fibers. The suture may be supplied with beaded ends, andsecured/overmolded with low molecular weight poylyethylene. Othersuitable fibers are polyesters, e.g. polyethylene terphthalate,polyamides, e.g. NYLON®, aramids, e.g. KEVLAR®, silk, biologics or thelike. Resorbable fibers may also be used in certain applications, e.g.those based upon polylactic acid, polyglycolic acid, or polydioxanone.

In a preferred embodiment, the anchoring assembly 1 will be provided inthe form of a kit. An exemplary kit might comprise an anchor kit andinstrumentation kit, including the following:

-   -   three sizes of anchors—S, M, L—each with a corresponding set        screw;    -   targeting template and trial jig for determining anchor position        and allowing joint manipulation and control—envisioned method of        control with radiograph, e.g. fluoro.    -   drill guides in three different sizes, one for each anchor size.    -   drill bits in three different sizes, one for each anchor size.    -   anchor impactor rods in three different sizes, one for each        anchor size.    -   screw driver for set screws including three different sizes of        Torx or hex drives with self retaining tips for securely holding        the set screws.        Each size anchor and set screw can be color coded by anodizing,        e.g. S—Brown, M—Blue, L—Green, for ease in matching sizes.        Preferably, the anchor impact rods are designed to mate with the        head 7 of the anchor member 5. The anchor impact rod would        impact the top 12 a of the head 7 of the anchor member 5, while        a central extension at the front of the anchor impactor rod        stabilizes the anchor member 5 onto the anchor impactor rod by        seating in the bore 8.

Different sizes of anchor assemblies are necessary to accommodatedifferent diameter tethers. The desired diameter tether will depend uponthe use of the internal bracing system and the joints being supported.Approximate overall dimensions of the three different sizes for theanchor and set screw may be as follows (in mm):

L M S Anchor Length 30 25 20 Bore Diam. 8 7 6 Head Diam 11 10 8.5 Setscrew Length 20 16 12 Diam. 6 5 4.2 Tether diam. 2.0 1.6 1.25

The anchor assembly can be used for internal bracing of many differenttypes of joints. To create an internal bracing system, two or moreanchor assemblies are positioned at various locations in the joint asnecessary to provide stability and allow proper movement of the joint.For example a first anchor 5 a is placed in a first bone 52 and a secondanchor 5 b is placed in a second bone 51. Preferably a third anchor 5 cis also placed in a first bone 52. A tether 20 passes through the firstanchor 5 a in the first bone 52 and is looped around the second anchor 5b in the second bone 51 and is terminated in a third anchor 5 c in thefirst bone 52. In any internal bracing system, each end of the tether isattached to one of the anchor assemblies. The tether may be loopedaround one or more additional anchor members (with or without the setscrew inserted therein), to provide the necessary stability and range ofmotion. Various configurations of internal bracing systems for differentjoints are disclosed herein. However, these bracing systems are merelyrepresentative of internal bracing systems which can be created usinganchoring assemblies of the present invention.

Knee Joint Internal Bracing

This invention serves the purpose of adding substantial control tounstable human knee joint through an ‘internal bracing’ extra-capsularmethod limiting the pathologic joint motions and internal slippage whichleads to the pathologic, destructive unstable motions which create highstresses and causes damage to the articular cartilage. Thesecircumstances are seen commonly post-trauma and in cultures with geneticlaxity and/or high demand knee performance, i.e. such as high stretchstates where the ligaments are permanently loosened, lengthened or torn.By adding this ‘internal brace’ control it is expected that these highstresses will be partially prevented and the slow progression ofarthritic wear, pain and instability of knee joints in theseindividuals.

Currently, when a knee becomes unstable, the first line of treatmentcould be an externally worn joint brace which have been used for manyyears but recently have been customized to the individual for better fitand function. Usually, these knee braces have been uncomfortable andineffective in providing the type of control and stability needed tocontrol pathologic sequelae of an unstable joint (ref: Hodge, Harman &Banks; J. of Arthroplasty; vol 24; #3, p 448; 2009). Surgical optionshave also existed for many years with intra-aricular ligamentreplacements and repairs which have used both biologic and artificialconstructs. These procedures involve major surgery with opening thejoint and primarily have involved restoring the cruciate ligaments whichare complex to install and have high failure rates becoming ineffectiveover time.

This invention repairs knees with stretched or torn ligaments byaugmenting and/or reinforcing these structures by an extra capsulartension band or internal brace configuration as illustrated in FIGS. 2and 3. This becomes an easy to insert, low cost solution to instabilityof the knee joint through a percutaneous surgery which implants this‘internal bracing’ or tension band like structure. This robustextra-capsular augment or ‘internal brace’ of the joint controlsstability using these simple artificial, biologic or hybrid extraarticular tension bands. This is done through this invention's abilityto restore the articular stability of the knee joint allowing it toreturn to a more normal motions, limiting the abnormal translations androtations which create high, abnormal stresses leading to joint damageand arthritis. The invention utilizes fiber materials made of strongsynthetic, biologic or hybrid materials with slight elastic properties.It can be attached to one of several types of fixed, adjustable,pivoting, expandable screw anchors with a pulley mechanism and/orrotational platform plate. These bone anchors are firmly fixed in bonewith a post device that avoids loosening and provides long-term biologicfixation. This device serves as the anchor for the single or doublearmed portion of the tension band which are attached by screws with orwithout a synthetic plate on the opposite side of the joint. Two or moreanchor screws may be used in anterior, posterior, medial or lateralcapsule of the knee.

Each knee joint will have a set of sized templates which identify theorigins and insertions of the medial, lateral collateral ligaments orpopliteal ligament which stabilize the joint. The template allows fortemporary pinning of the location of the permanent anchors. Utilizingthese, the extra-articular tension bands are attached to these temporaryposts allowing the joint to be tested for stability while taken througha natural range of motion. Once the desired stability is obtained, thelocations are marked and the permanent anchors are inserted for finaltrialing and tensioning.

For precise placement of actual knee joint internal bracing,fluoroscopic, radiographic, or ultrasonic analysis can provide an intraoperative view with or without 3D animations looking at actual internalknee motions defining the active, dynamic function and efficacy of thisnew invention. This will demonstrate basic improvements in knee jointfunction and stability. Human joint kinematic testing of the knee jointstability will be performed post-op with high speed camera (Vicon)motion analysis before and after application of the ‘Internal Brace.’

Femoral Patellar Internal Bracing

The femoral patellar join is one of the most unstable joints in thebody. Sometimes this is do to injury but many times may relate togenetic ligament laxity or a congenitally shallow femoral patellargroove. The ligament that is most important in patellar stability is themedial patellar femoral Ligament complex (MPFL). With this new boneanchor/tension band system, this ligament can be recreated to givepatellar stability and knee strength with reduced pain of mal tracking.The main bone anchor is place near the medial femoral epicondyle withtwo simple bone anchors in the patella creating a two pole recreation ofthe MPFL, as illustrated in FIG. 11.

Ankle Joint Internal Bracing

The ankle joint is the most injured and causes the most disability ofany joint injury. This is primarily due to ankle sprains and strainswhich are due to ligament laxity and tears. As with the knee as statedabove, the ‘internal brace concept’ works extremely well in the ankleproviding needed stability. The ankle is a mortice type of joint thathas mainly anterior, medial and lateral ligaments and any or all ofthese can become stretched or torn leading to high stresses andarticular damage with arthritis. Some individuals have inherent laxityof these ligaments while others have chronic injuries to this joint.

The current treatments of these ankle instabilities are usually wearinga brace or high top shoe with reinforced strapping. These are cumbersomeand uncomfortable so many times are only worn infrequently. As with theknee also, there are surgical methods of various types of ligamentreinforcers and reconstruction mostly using nearby tendons which areharvested for application to usually medial or lateral aspects of theankle joint. These operations diminish ankle function by removing one ormore nearby tendons and have traditionally not held up over time becauseof stretching out or rupturing.

This invention takes unstable ankles with stretched or torn ligamentsand augments and reinforces these structures with an extra capsulartension band or internal brace configuration. This becomes a simple, lowcost solution to instability of the ankle joint with a percutaneoussurgery which implants this ‘internal bracing’ or tension band likestructure. This robust extra-capsular augment or ‘internal brace’ of thejoint controls stability using these simple artificial, biologic orhybrid reinforcers or tension bands. This is done through thisinvention's ability to restore the articular position of the ankle jointallowing it to return to a more normal motions, limiting the abnormaltranslations and rotations which create high, abnormal stresses leadingto joint damage and arthritis. The invention utilizes theseextra-articular tension band mechanism made of strong synthetic,biologic or hybrid materials with slight elastic properties. It isattached to one of several types of fixed, adjustable, pivoting,expandable screw anchors with a pulley mechanism and/or rotationalplatform plate. These bone anchors are firmly fixed in bone with a postdevice that avoids loosening and provides long-term biologic fixation.This device serves as the anchor for the single or double armed portionof the tension band which are attached by screws with or without asynthetic plate on the opposite side of the joint. Two or more screwsmay be used in anterior, posterior, medial or lateral and can beassociated with locking, capture inserts at the extremes of the plate.

The ankle joint has a set of templates which identify where the originsand insertions of the Deltoid medial collateral, lateral fibularcollateral ligaments and anterior tibial talar ligament which providethe primary stability of the joint. The template allows for temporarypinning of the location of the permanent anchors. Utilizing these, theextra-articular tension bands are attached to these temporary postsallowing the joint to be tested for stability while taken through anatural range of motion. Once the desired stability is obtained, thelocations are marked and the permanent anchors are inserted for finaltrialing and tensioning.

Human joint kinematic testing of the ankle joint stability will beperformed with high speed camera (Vicon) motion analysis before andafter application of the ‘Internal Brace.’ This will demonstrate basicimprovements in ankle joint function and stability. For more precisemeasurements of actual ankle joint internal mechanics, fluoroscopic,radiographic, or ultrasonic analysis can provide an internal view andanimations looking at actual internal ankle motions defining the active,dynamic function and efficacy of this new invention.

Spine Internal Bracing

The spine becomes unstable with advancing age and disease. The goals ofmodern spine surgery are to obtain stability while maintaining motion.This new invention allows ‘internal bracing of the spine by setting uptension bands utilizing our novel bone anchoring system which allowsrotations and translations of the spine while providing a stabilizingelement. These tension bands can be anterior or lateral fixing to twoadjacent vertebral bodies or can be posterior and go between spinousprocesses. These simple tension bands can be used in conjuction withimplants such as artificial discs to provide the correct tension forthese devices to remain stable.

Separated Shoulder Internal Bracing

When a shoulder is injured with so called ‘separation’ this refers to adisruption of the acromioclavicular joint and the coracoclavicularligament. This can be difficult to repair, but with our new boneanchor/tension band system it is simplified. The bone anchor is placedin the distal clavicle while the tension band is wrapped around thecoracoid process reconstructing the coracoclavicular ligament while theacromioclavicular joint heals or fibroses.

Wrist Internal Bracing

The dorsal radiocarpal ligaments are commonly injured and becomeunstable with age. These ligaments can now be reconstructed with ournovel bone anchor tension banding system by placing one or more anchorsin the distal radius and spaning the dorsal wrist joint to place otheranchors in the proximal row of carpal bones. This provides an excellent‘internal bracing’ mechanism restoring the patients grip strength andfunction.

All patents and publications mentioned in this specification areindicative of the levels of those skilled in the art to which theinvention pertains. All patents and publications are herein incorporatedby reference to the same extent as if each individual publication wasspecifically and individually indicated to be incorporated by reference.

It is to be understood that while a certain form of the invention isillustrated, it is not to be limited to the specific form or arrangementherein described and shown. It will be apparent to those skilled in theart that various changes may be made without departing from the scope ofthe invention and the invention is not to be considered limited to whatis shown and described in the specification and any drawings/figuresincluded herein.

One skilled in the art will readily appreciate that the presentinvention is well adapted to carry out the objectives and obtain theends and advantages mentioned, as well as those inherent therein. Theembodiments, methods, procedures and techniques described herein arepresently representative of the preferred embodiments, are intended tobe exemplary and are not intended as limitations on the scope. Changestherein and other uses will occur to those skilled in the art which areencompassed within the spirit of the invention and are defined by thescope of the appended claims. Although the invention has been describedin connection with specific preferred embodiments, it should beunderstood that the invention as claimed should not be unduly limited tosuch specific embodiments. Indeed, various modifications of thedescribed modes for carrying out the invention which are obvious tothose skilled in the art are intended to be within the scope of thefollowing claims.

What is claimed is:
 1. An internal bracing system for a joint of a bodycomprising: a suture; a first bone anchor for positioning in a firstbone of a joint; a second bone anchor positioned in a second bone of ajoint; a third bone anchor for positioning in the first bone of a joint;wherein the suture connects the first bone anchor to the second boneanchor and connects the second bone anchor to the third bone anchor in amanner which stabilizes the joint; wherein each of the bone anchorscomprises: an anchor member comprising a longitudinal threaded bore, anannular channel on a head for receiving the suture, a straight channelextending on a diameter of the head portion for receiving the suture andintersecting the annular channel at opposing ends of the annularchannel, a plurality of longitudinal structures on a shaft, each of thelongitudinal structures comprising a series of protrusions; and a setscrew threadably insertable into the longitudinal threaded bore.
 2. Theinternal bracing system according to claim 1 wherein the bone anchorsare arranged to retain a portion of the suture.
 3. The internal bracingsystem according to claim 1 wherein the at least one bone anchorincludes a bone anchor assembly including: an anchor member having acentral bore therein for insertion into the bone; a set screw insertableinto the bore of the anchor member such that the suture is retainedbetween the set screw and the bore of the anchor member when the setscrew is inserted in the bore.
 4. The internal bracing system accordingto claim 3 wherein the suture is formed of a high strength-high modulusfiber selected from a group comprising: oriented ultra high molecularweight polyethylenes, polyesters, polyamides, aramids, silk andbiologics.
 5. The internal bracing system according to claim 4, whereinthe suture is formed of a plurality of fibers which are free of eachother in the form of a bundle.
 6. The internal bracing for human jointsaccording to claim 1, wherein the joint is from the group comprising: afemoro-tibial joint, a patello-femoral joint, an ankle, an elbow, and ashoulder.
 7. the internal bracing system of claim 1 where in the suturecomprises ultra high molecular weight polyethylenes.